Conventionally, in CDMA (Code Division Multiple Access) communication and the like, a mobile station saves power consumption by bringing unnecessary circuits thereof to a low power consumption mode. In more detail, a mobile station adopts an intermittent reception method by which, in the standby state waiting for a call from the base station, only paging channel slots assigned to the mobile station are monitored within a paging channel transmitted from the base station (e.g. refer to a technology disclosed in an international publication number WO93/18596). While not performing the monitoring, the mobile station saves power consumption by bringing unnecessary circuits thereof to a low power consumption mode.
A paging channel is used in transmission of control information, call information, and the like, from a base station to a mobile station. The paging channel is divided into slots each having 80 ms. Each slot is called a paging channel slot, and the base station transmits a message to a particular mobile station at a particular cycle of paging channel slots (this cycle is called “slot cycle”). In this structure, the mobile station is able to monitor the paging channel slots directed to itself according to the slot cycle.
Currently, there are many use patterns of a mobile terminal (i.e. mobile station), and it is no longer necessary to monitor the paging channel always at a certain cycle in the standby state. Rather, it has become desirable to attempt power consumption saving by changing the monitoring cycle according to the current use pattern of the mobile terminal.